Quantitative chemical mapping of InGaN quantum wells from calibrated high-angle annular dark field micrographs

Daniel Carvalho, Francisco M. Morales, Teresa Ben, Rafael García, Andrés Redondo-Cubero, Eduardo Alves, Katharina Lorenz, Paul R. Edwards, Kevin P. O'Donnell, Christian Wetzel

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We present a simple and robust method to acquire quantitative maps of compositional fluctuations in nanostructures from low magnification high-angle annular dark field (HAADF) micrographs calibrated by energy-dispersive X-ray (EDX) spectroscopy in scanning transmission electron microscopy (STEM) mode. We show that a nonuniform background in HAADF-STEM micrographs can be eliminated, to a first approximation, by use of a suitable analytic function. The uncertainty in probe position when collecting an EDX spectrum renders the calibration of HAADF-STEM micrographs indirect, and a statistical approach has been developed to determine the position with confidence. Our analysis procedure, presented in a flowchart to facilitate the successful implementation of the method by users, was applied to discontinuous InGaN/GaN quantum wells in order to obtain quantitative determinations of compositional fluctuations on the nanoscale.
Original languageEnglish
Pages (from-to)994-1005
Number of pages12
JournalMicroscopy and Microanalysis
Issue number4
Early online date30 Jun 2015
Publication statusPublished - Aug 2015


  • chemical mapping
  • energy dispersive X-ray spectroscopy
  • InGaN/GaN quantum well
  • RBS
  • EDX

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